Biomass (bioresource) is originally generated by taking in carbon dioxide from the atmosphere. Thus, biomass is a carbon-neutral resource in that carbon dioxide concentration in the atmosphere is not increased or decreased in the case of being combusted, which is different from the case of combusting a fossil fuel. Hence, research for using such carbon-neutral biomass is currently advanced.
Biomass-derived components such as cellulose, chitin, protein, and terpenoid include functional groups which are appropriate for binding with functional groups of other compounds such as a hydroxyl group, a phenolic group, a mercapto group, an amino group, a carboxyl group, and a double bond.
Thus, there is a great expectation in an attempt to modify biomass under a chemical reaction for creating a novel product which develops high functionality.
In order to effectively achieve the above-described attempt, it is required that an intended chemical reaction in biomass-derived components proceeds evenly and rapidly as a whole.
However, solid-phase biomass has high crystallinity and aggregated structure including, e.g., a three-dimensional cross-link for keeping biological functions. Thus, there is a concern that approach of a reaction reagent to functional groups of biomass-derived components may be prevented and homolytic chemical reaction may be inhibited.
For the above reason, when a product using biomass as its material is manufactured, improvement of reactivity and dispersibility is attempted by performing pulverization processing of degrading aggregated structure of biomass in a process of reacting biomass with various types of reagents and/or compounding or in its preceding process (e.g., refer to the following Patent Documents 1 to 3).
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-289164
[Patent Document 2] Japanese Patent No. 4660528
[Patent Document 3] Japanese Patent No. 5481623
The Patent Document 1 discloses technology of obtaining homogeneous suspension liquid by (a) mixing biomass with a solvent using a high-pressure homogenizer and (b) micronizing the mixed biomass by actions of the high-pressure homogenizer such as shear pulverization, collisional destruction, cavitation destruction, and pressure to disperse the micronized particles of biomass into the solvent.
However, one operation of the above-described process using a homogenizer does not have a sufficient effect of degrading aggregated structure, and plural times of operations are sometimes required. Further, the above-described process using a homogenizer has a problem of inefficiency because it consumes a great amount of solvent.
The Patent Document 2 discloses technology of obtaining suspension in which biomass is finely dispersed into an organic solvent, by (a) feeding biomass and the organic solvent into a temperature-adjustable closed container and (b) kneading them under high temperature and high pressure to degrade aggregated structure of the biomass.
However, it takes a long time to set the biomass and the solvent at normal temperature and normal pressure to intended temperature and intended pressure, and a great amount of energy is lost in it. Thus, it has problems of low-productivity and high manufacturing cost.
Additionally, if kneading time is prolonged in order to improve the effect of degrading aggregated structure, it causes another problem of reducing molecular mass of biomass.
The Patent Document 3 discloses technology of manufacturing composite compound by (a) performing heat treatment on woody material, which has been subjected to a mechanically dry grinding process, with water vapor to attenuate crystalline bonding strength under hydrolysis and then (b) mixing the resultant woody material with resin.
However, grain size of the woody material composing the manufactured composite compound is determined depending on the grinding process. Thus, there is a problem that to form homogeneous and fine disperse phase is difficult in the case of large grain size and the strength of the composite compound is degraded due to reduction in molecular mass in the case of small grain size.